RRB NTPC CBT 2 Level 5 June-12-2022 Shift 1 Exam Previous Question Paper with Solutions

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41) Sudhir is 4.5 times as efficient as Aarav. If they work together, they can complete a piece of work in 8 days. How many days will Aarav take to do the same work alone?

A) 36
B) 48
C) 44
D) 40

View Answer

C) 44

Explanation:We are given:
* Sudhir is 4.5 times as efficient as Aarav
* Together, they complete the work in 8 days
We are to find how many days Aarav alone would take.
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Step-by-step Shortcut:
Let Aarav’s efficiency = 1 unit/day, so Sudhir = 4.5 units/day
→ Combined efficiency = $1 + 4.5 = 5.5$ units/day
Total work = Efficiency × Time =
$5.5 × 8 = 44 \text{ units}$
Now, Aarav alone does 1 unit/day, so:
$\text{Time} = \frac{44}{1} = \boxed{44 \text{ days}}$
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✅ Final Answer: Option 3. 44 days ✅

42) Which of the following countries does NOT have direct access to a sea?

A) Myanmar
B) Bangladesh
C) Nepal
D) Pakistan

View Answer

C) Nepal

43) A solid metallic sphere of radius 3 cm is melted and drawn into a wire of thickness 4 mm.What is the length of the wire (in m)?

A) 9.25
B) 7.5
C) 9
D) 8

View Answer

C) 9

Explanation:To find the length of the wire formed by melting a solid metallic sphere, we’ll follow these steps:
Given:
– Radius of the sphere (r): 3 cm
– Thickness (diameter) of the wire (d): 4 mm = 0.4 cm
*(Note: Thickness refers to the diameter, so the radius of the wire $r_w = \frac{d}{2} = 0.2$ cm)*
Step 1: Calculate the Volume of the Sphere
The volume $V$ of a sphere is given by:
$V = \frac{4}{3} \pi r^3$
Substituting r = 3 cm:
$V = \frac{4}{3} \pi (3)^3 = \frac{4}{3} \pi × 27 = 36\pi \text{ cm}^3$
Step 2: Relate the Volume to the Wire
When the sphere is melted and drawn into a wire, the volume remains the same. The wire is a cylinder with:
– Radius $r_w$ : 0.2 cm
– Length $L$ : To be found
The volume of the cylinder (wire) is:
$V = \pi r_w^2 L$
Setting this equal to the sphere’s volume:
$\pi (0.2)^2 L = 36\pi$
Simplify:
0.04 L = 36
$L = \frac{36}{0.04} = 900 \text{ cm}$
Step 3: Convert Centimeters to Meters
$900 \text{ cm} = 9 \text{ m}$
Final Answer:
$\boxed{9}$